This invention relates generally to recording mediums and more particularly to metallized recording mediums in which the metal surface is eroded to expose an underlying layer of contrasting color.
Metallized papers having a thin layer of metal thereon which is erodible by recording electrodes are well known. These papers are usually coated with metal which is sputtered or evaporated over the surface of the paper in an extremely thin layer a several hundred Angstroms in thickness. The metal coating covers either a dark paper or a paper having an intermediate layer which contrasts with the color of the metal coating so that, when exposed, the covered layer provides easily readable marks. The papers may be coated with any of several different metals but the usual metal is aluminum which provides a bright, shiny surface having the silver coloring of the aluminum. There is some reluctance in certain recording applications, to use this record medium because of the brightness of the surface since a dull or matte finish is preferred.
Past attempts at providing muted, more acceptable surface finishes have tried coating with different metals such as zinc, nickel, tin, copper or bronze. (See U.S. Pat. Nos. 1,825,551 and 2,833,677.) Usually the coating of these other metals requires more processing or more expensive metallizers to achieve the coating. These other metals are able to provide some differences in color, but their expense is a significant disadvantage. Another drawback of other metals is the variation in surface resistivity which requires different energies for the recording erosion. This further requires changing the printer marking energy to conform to that necessary to remove coat and is the most attractive of the metallized papers. Heretofore, however, its acceptance has been slow because of the metallic sheen.
Metallized paper has been used heretofore in certain applications such as decorative packaging or labels. In these instances, overprinting of the metal with designs or information may be required. However, there has been no application of ink where the metal coating was intended for removal.